So far, two interesting links merit mentioning: First, it was recently shown that the gene expression of allele HLA-DRB1*1501 is modulated by VD, and a highly conserved VD-responsive element has been identified in the promoter region of the HLA-DRB1*1501 haplotype, which may indicate a direct functional interaction between VD and the major locus determining genetic susceptibility to MS [68]. This evidence concerns the gene HLA-DRB1 and myeloid sarcoma.